At the moment of filing this application, the most general form of mobile personal telecommuication is a second-generation digital cellular radio network; these networks include the European systems GSM (Global system for Mobile telecommunications) and its extension DCS1800 (Digital Communications System at 1800 MHz), the North American (USA) systems IS-136 (Interim Standard 136), IS-95 (Interim Standard 95) and the Japanese system PDC (Personal Digital Cellular). These systems transmit mainly speech, telefaxes and short text messages, as well as digital data at a limited speed, for instance files transmitted between computers. Several third-generation systems are being designed, the aims being world-wide coverage, a large selection of data transmission services and a flexible sharing of capacity, so that a given user may, when desired, transmit and/or receive even a large amount of data at a high speed.
The European Telecommunications Standards Institute ETSI has suggested a third-generation mobile telecommunications system called UMTS (Universal Mobile Telecommunications System). Its aim is a wide operating environment including homes, offices, urban and rural environments as well as stationary and mobile stations. The selection of services is large, and in addition to the currently known mobile telephones, the types of mobile stations include for instance multimedia terminals and multipurpose terminals that mediate telecommunications between the UMTS system and various local systems.
FIG. 1 illustrates an exemplary cell 11 of the UMTS system, provided with a stationary base station subsystem 12 (BSS), within the range of which there exist or move, along with the users, several different mobile stations 13. The base station subsystem may comprise one or several base stations, as well as a base station controller controlling their operation. In between the base station subsystem and the mobile stations, there is a radio connection, for which a given radio frequency range is reserved, and the operation of which is regulated by the specifications of the system. The time and frequency range available for the radio connection together define so-called physical radio resources. One of the biggest challenges of the base station subsystem is to control the use of these physical radio resources so that all terminals located in the cell coverage are at any moment capable of receiving data transmission services of the requested quality, and that adjacent cells interfere with each other as little as possible.
From the prior art systems, there are known several methods for sharing radio resources. In time division multiple access (TDMA), each of the employed transmission and reception frequency bands is divided into time slots, among which the base station subsystem allocates one or several cyclically repeated time slots to the use of a given terminal. In frequency division multiple access (FDMA), the utilised frequency range is divided into very narrow bands, among which the base station subsystem allocates one or several to each terminal. Many current systems apply a combination of these, where each narrow frequency band is further divided into time slots. In coded division multiple access (CDMA), each connection between the mobile station and the base station subsystemobtains a spreading code, whereby the transmitted information is spread randomly within a fairly large frequency range. The codes used within the cell coverage are mutually orthogonal or nearly orthogonal, in which case a receiver that recognises the code may distinguish the desired signal and attenuate other simultaneous signals. In orthogonal frequency division multiplex (OFDM), suited mainly for broadcasting-type services, data is transmitted from the transmitting central station on a wide frequency band, which is divided into equidistant sub-frequencies, and the simultaneous phase shifts of these sub-frequencies create a two dimensional bit flow in the time-frequency space.
As for the technology of packet switched radio networks, there are also known various packet-based connection protocols, where the connection between the mobile station and the base station subsystemis not continuous but proceeds in packages with pauses of varying durations in between. Compared with continuous connection Systems, i.e. with so-called circuit-switched networks, there is achieved the advantage that the radio resources required by a given connection are not unnecessarily occupied when there is a temporary pause in the connection. A drawback is generally a longer data transmission delay, because after each pause, the transmission of a new packet requires the exchange of certain control or signalling messages between the mobile station and the base station. Delays can also be caused by different routing of the packages between transmitter and receiver.
It is typical of third-generation cellular radio networks that for instance in the case of FIG. 1, with some of the terminals 13 it suffices to have a fairly low-capacity radio connection with the base station, but some of them need, at least temporarily, a remarkably larger share of the common radio resources than the others. Low-capacity connections can be for example speech connections, and a high-capacity connection can be for example the loading of an image file in a data network connection via the base station subsystemto the mobile station, or a video image connection during a videophone call. In the prior art, there is not known a method where the base station subsystem could divide the available radio resources in a flexible and dynamic way between the various users.